Various types of video compression are typically employed in both the storage and transmission of compressed video data that represents motion video. Among those types of video compression are versions of the widely used Motion Picture Experts Group (MPEG) specification promulgated by the International Organization for Standardization of Geneva, Switzerland. Specifically, versions of MPEG known widely as MPEG 2 and MPEG 4 (also known as H.264) have been widely adopted for use in transmitting motion video via satellite, through over-the-air and cable-based distribution systems, and as streamed data via networks (e.g., the Internet). Currently under development is a new version of MPEG known among its developers as high-efficiency video coding (“HEVC”) or “H.265” that updates various aspects of MPEG to better address the commonplace adoption of “high definition” television resolutions.
The widespread adoption of such types of video compression has gone hand in hand with the development of new generations of viewing devices able to support new features, including the use of thumbnail images to provide previews of motion videos and/or a visual index of portions of a motion video. Thumbnail images are typically reduced-sized versions of at least some of the full-resolution frames of a motion video, often having a resolution of only up to 200×200 pixels, versus the now commonplace 1920×1080 pixels of full-resolution frames. It is also common for thumbnail images to have a lesser per-pixel color depth than their counterpart full-resolution frames (e.g., 8 bits per pixel for a thumbnail image versus 16 or 24 bits per pixel for a full-resolution frame).
Their lesser resolution and/or color depth result in thumbnail images having a considerably smaller data size than corresponding full-resolution frames depicting the same image such that visually presenting thumbnail images could be significantly less processor-intensive than visually presenting full-resolution frames. Unfortunately, it has become commonplace to employ types of compression (e.g., MPEG 2, MPEG 4, etc.) and implementations of compression coder-decoder (CODEC) hardware and/or software that supports only a single resolution such that only full-resolution frames are typically transmitted or stored. As a result, viewing devices currently must derive thumbnail images by first decompressing and/or decrypting corresponding full-resolution frames, and then downscaling those full-resolution frames to create the thumbnail images.
Thus, viewing devices are denied the potential benefits of reduced processing demands that the smaller data size of thumbnail images could provide. This can become a significant issue for portable viewing devices that rely upon a battery for electric power, since higher processing demands typically lead to higher rates of power consumption.